1. Field of the Invention
The present invention relates to an apparatus and method for matching sequences of phonemes or the like. The invention can be used to search a database of data files having associated phonetic annotations, in response to a user's input query. The input query may be a voiced or typed query.
2. Description of the Related Art
Databases of information are well known and suffer from the problem of how to locate and retrieve the desired information from the database quickly and efficiently. Existing database search tools allow the user to search the database using typed keywords. Whilst this is quick and efficient, this type of searching is not suitable for various kinds of databases, such as video or audio databases.
A recent proposal has been made to annotate such video and audio databases with a phonetic transcription of the speech content in the audio and video files, with subsequent retrieval being achieved by comparing a phonetic transcription of a user's input query with the phoneme annotation data in the database. The technique proposed for matching the sequences of phonemes firstly defines a set of features in the query, each feature being taken as an overlapping fixed size fragment from the phoneme string, it then identifies the frequency of occurrence of the features in both the query and the annotation and then finally determines a measure of the similarity between the query and the annotation using a cosine measure of these frequencies of occurrences. One advantage of this kind of phoneme comparison technique is that it can cope with situations where the sequence of words of the query do not exactly match the sequence of words of the annotation. However, it suffers from the problem that it is prone to error especially when the query and the annotation are spoken at different speeds and if there are any deletions of parts of words from the query, but not from the annotation, or vice versa.